• Title/Summary/Keyword: Military Power

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Sand particle-Induced deterioration of thermal barrier coatings on gas turbine blades

  • Murugan, Muthuvel;Ghoshal, Anindya;Walock, Michael J.;Barnett, Blake B.;Pepi, Marc S.;Kerner, Kevin A.
    • Advances in aircraft and spacecraft science
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    • v.4 no.1
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    • pp.37-52
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    • 2017
  • Gas turbines operating in dusty or sandy environment polluted with micron-sized solid particles are highly prone to blade surface erosion damage in compressor stages and molten sand attack in the hot-sections of turbine stages. Commercial/Military fixed-wing aircraft engines and helicopter engines often have to operate over sandy terrains in the middle eastern countries or in volcanic zones; on the other hand gas turbines in marine applications are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly-ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The focus of this research work is to simulate particle-surface kinetic interaction on typical turbomachinery material targets using non-linear dynamic impact analysis. The objective of this research is to understand the interfacial kinetic behaviors that can provide insights into the physics of particle interactions and to enable leap ahead technologies in material choices and to develop sand-phobic thermal barrier coatings for turbine blades. This paper outlines the research efforts at the U.S Army Research Laboratory to come up with novel turbine blade multifunctional protective coatings that are sand-phobic, sand impact wear resistant, as well as have very low thermal conductivity for improved performance of future gas turbine engines. The research scope includes development of protective coatings for both nickel-based super alloys and ceramic matrix composites.

Identification of Usable Geographic Information for Pilot of Forest Fire Suppression Helicopter and Its Acquisition from Public Data (산불진화헬기 조종사에게 유용한 지리정보의 식별 및 공공 자료로부터의 획득 방안)

  • Ryu, Young-Ki;Kim, Man-Kyu;Park, Jong-Chul
    • Journal of the Korean Association of Geographic Information Studies
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    • v.14 no.3
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    • pp.52-67
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    • 2011
  • The research investigates the identification of necessary geographic information needed by forest fire suppression helicopter pilots, and the ways to acquire the required information from public institutions. Firefighting helicopter pilots demand 7 physical geographic and 13 human geographic data. Applying the geographical information acquired from Korean public institutions, the following 15 characteristics (3 physical geographic, 12 human geographic) can be found: altitude and highlands, river, high population and urban areas, roads, national park and state boundaries, fuel re-supply facilities, freshwater areas, cultural assets, (LPG)gas charging stations, gas stations, ammunition storage areas, ground power cables, and steel towers. Within the database of physical geography, there is a need for improvement on bird habitat details. Also, the availability of visibility, wind directions, and wind velocity data is limited and therefore requires refining. The location of refueling areas can be obtained by applying information received from institutions to the GIS spatial analysis.

A Study on Japanese and Foreign Place Names in Google Earth Satellite Images and GNS Database on South Korea (구글어스의 위성영상과 미국의 지명데이터베이스에 나타나는 한국내 일본식 및 외국어 지명에 관한 연구)

  • Park, Kyeong;Chang, Eun-Mi
    • Journal of the Korean Geographical Society
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    • v.43 no.2
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    • pp.188-201
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    • 2008
  • With recent rapid globalization, accurate information for the foreign countries is increasingly important. Errors based on inaccurate information and unequal international relationships complicate the situations. In this article, authors analyzed the Japanese place names which appear on the Google Earth images and place name database of the NGA. Google Earth already becomes a tremendous soft power in internet society; therefore, accurate information on the satellite image is more necessary than ever. This article finds that many types of errors exist in the place names in Google Earth image service. Also many place names are listed with Japanese pronunciation in GNS database as variants. The Japanese place names have not been used in topographic maps published since 1910s and 1930s. Japanese place names were widely used in US military maps published in 1946. 1:250,000 maps published in 1954, however, doesn't seem to use Japanese pronunciation any more.

Hormesis as a Confounding Factor in Epidemiological Studies of Radiation Carcinogenesis

  • Sanders Charles L.
    • Journal of Radiation Protection and Research
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    • v.31 no.2
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    • pp.69-89
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    • 2006
  • Biological mechanisms for ionizing radiation effects are different at low doses than at high doses. Radiation hormesis involves low-dose-induced protection and high-dose-induced harm. The protective component is associated with a reduction in the incidence of cancer below the spontaneous frequency, brought about by activation of defensive and repair processes. The Linear No-Threshold (LNT) hypothesis advocated by the International Commission on Radiological Protection (ICRP) and the Biological Effects of ionizing Radiation (BEIR) Report VII for cancer risk estimations Ignores hormesis and the presence of a threshold. Cancer incidences significantly less than expected have been found in a large number of epidemiological studies including, airline flight personnel, inhabitants of high radiation backgrounds, shipyard workers, nuclear site workers in scores of locations throughout the world, nuclear power utility workers, plutonium workers, military nuclear test site Participants, Japanese A-bomb survivors, residents contaminated by major nuclear accidents, residents of Taiwan living in $^{60}Co$ contaminated buildings, fluoroscopy and mammography patients, radium dial painters, and those exposed to indoor radon. Significantly increased cancer was not found at doses <200 $mSv^*$. Evidence for radiation hormesis was seen in both sexes for acute or chronic exposures, low or high LET radiations, external whole- or partial body exposures, and for internal radionuclides. The ubiquitous nature of the Healthy Worker Effect (HWE)-like responses in cellular, animal and epidemiological studies negates the HWE as an explanation for radiation hormesis. The LNT hypothesis is wrong and does not represent the true nature of the dose-response relationship, since low doses or dose-rates commonly result in thresholds and reduce cancer incidences below the spontaneous rate. Radiation protection organizations should seriously consider the cost and health implications of radiation hormesis.

Design of Intrustion Prevention System(IPS) in Linux Environment (리눅스 환경에서의 침입방지시스템(IPS) 설계)

  • 이상훈;김우년;이도훈;박응기
    • Convergence Security Journal
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    • v.4 no.2
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    • pp.1-7
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    • 2004
  • The growth of incidents on the Internet has reflected growth of the internet itself and growth of the computing Power. while in Previous years, external attacks tended to originate from those interested trend in exploring the Internet for its own sake and testing their skills, there is an increasing trend towards intrusions motivated by financial, Political, and military objectives. so, attacks on the nation's computer infrastructures are becoming an increasingly serious problem. Even though the problem is ubiquitious, government agencies are particularly appealing targets and they tend to be more willing to reveal such events than commercial organizations. The threat of damage made necessity of security's recognition, as a result, many researches have been carried out into security of system actively. Intrusion Detection technology is detection of intrusion using audit data differently from using traditional simple filtering and informs manager of it. It has security manager of system deal with the intrusion more quickly. but, cause current environment of Internet manager can't doing response Intrusion alert immediately That's why IPS needed. IPS can response automatically the intrusion alert. so, manager is more comfortable and can response quickly.

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Empirical Analysis of the Back and Forth Relationship Between China and U.S since 1989: focusing on the Jiangzemin and Clinton's cognitive map (1989년 이후 이중적 중미관계: 장저민과 클린턴의 인지지도 분석을 중심으로)

  • Chung, Da Hoon
    • Korean System Dynamics Review
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    • v.13 no.3
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    • pp.47-66
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    • 2012
  • This paper aims at investigating and identifying the factor that has led the back and forth relationship between China and the United States since 1989. Previous studies on this subject addressed the issue by taking either of two approaches: one with the micro view that interprets the back and forth relationship in the context of the end of the Cold war, on other hand, with the macro view that interprets the fragile relationship in the context of the rise of China. However, neither of the approaches explains with sufficiency the question at hand. Hence for the inquiry, this article suggests a fresh view by exploring alternative method of using a cognitive map of each nation's leader, Jiangzemin and Bill Clinton. This article provides an empirical analysis through the Selected works of Jiangzemin and the speeches of Bill Clinton in 1998 for the first time in the field of Sino-US relationship studies in Korea. With the results of the cognitive map analysis, we can reach the following four points. Firstly, indicators of the forth relationship between China and the US are: i) the recognition by Bill Clinton on the importance of China's economic growth and; ii) the US's cooperation of science technology with China. Second, the conflict between China and the US results from the discordance of opinions on the matter of human rights and military power. Second, the conflict will inevitably arise on environmental issues around the globe including a global warming. Third, while China has yet to find a legitimate reason to agree upon these issues with the US, the US urges China of its cooperation. Lastly, Both China and the US attach great importance to the alliance with Japan. This implicates that relatively, issues involving Japan take more control in the China-US relationship, than those of Korea Peninsula.

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Interference Analysis of Wireless Systems with Arbitrary Antenna Patterns and Geographic Information in the VHF/UHF Bands (VHF/UHF 대역에서 지리정보와 임의 안테나 패턴을 갖는 무선시스템의 간섭분석 연구)

  • Suh, Kyoung-Whoan
    • Journal of Broadcast Engineering
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    • v.18 no.3
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    • pp.445-454
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    • 2013
  • By using the radio propagation prediction of Rec. ITU-R P.1546, geographic information system, and S-I plane, we presented the methodology of interference analysis based on the minimum coupling loss, and also suggested the local coordinate system for calculating azimuth and elevation angles between the victim receiver and the interferer for an arbitrary antenna pattern. To check the presented algorithm, the map with the land-sea mixed area was taken for the given area of $80{\times}60[km^2]$ as real geography information. Field strength, path profile, and protection ratio with maximum allowable interference level have been illustrated for radar and fixed wireless system for the assumed frequency. In addition interference power of the victim receiver was calculated asa function of azimuth and elevation angles of the interferer. The developed methodology of interference analysis in the VHF and UHF bands can be actually applied to assess interoperability as well as compatibility in the civil or military applications.

Technical Trends for Fuel Cell Aircraft (연료전지항공기 기술 동향)

  • Kim, Keun-Bae
    • Current Industrial and Technological Trends in Aerospace
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    • v.7 no.2
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    • pp.95-105
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    • 2009
  • Fuel cells are applied to the propulsion system of aircraft based on environmental-friendly characteristics with low noise and zero emission of CO2, currently many kinds of UAV and small manned aircraft equipped with fuel cells are being developed. Fuel cells for aircraft typically classified into PEMFC(Proton Exchange Membrane Fuel Cell) type and SOFC(Solid Oxide Fuel Cell) type and the system is developed to adapt missions and operational conditions of aircraft. For UAV, various types of aircraft mostly based on PEM fuel cell technology are investigated for military or commercial uses, and the stability and endurance of system will be improved. For small manned aircraft, many researches are carried out to substitute the propulsion system by fuel cell, also some developments for the higher performance of APU of large commercial aircraft to apply fuel cells are in progress. In the future, a fuel cell aircraft will be expected to improve the reliability and efficiency with higher power density.

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Output SINR Analysis of GPS Adaptive Interference Canceler Based on Modified Despreader (변형된 역확산기 기반의 GPS 적응 간섭제거기의 출력 SINR 해석)

  • Hwang, Suk-Seung
    • The Journal of the Korea institute of electronic communication sciences
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    • v.9 no.2
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    • pp.195-202
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    • 2014
  • The Global Positioning System (GPS), which has various military and commercial applications, is designed to estimate the location of the specific user or object. In order to accurately estimate the location, GPS requires at least four satellite signals. The GPS receiver operates on extremely low signal-to-noise ratio (SNR) environment and it may suffer from various interference signals with the extremely high power. In this paper, we introduce a blind adaptive receiver based on the modified despreader, which suppress interference signals and detect GPS signals of interest without requiring explicit angle-of-arrival (AOA) information. We, also, provide the mathematical analysis for the signal-to-interference and noise ratio (SINR) of the modified despeader beamformer output. A representative computer simulation example is presented to illustrate the interference suppression performance of the considered GPS receiver and mathematical analysis of the SINR.

Qualification Process of T700/701K Engine for KUH (한국형 기동헬기 엔진 (T700/701K) 인증 과정)

  • Jung, Yong-Wun;Kim, Jae-Hwan;Ahn, Iee-Ki
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.11a
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    • pp.344-347
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    • 2011
  • This paper presents qualification process of the T700/701K turbo-shaft engine for Korean Utility Helicopter(KUH). The T700/701K is the rear-drive variant of the GE's T700-701C/D engine which was qualified for military applications in the world. The main scope of the development is the modification from a front-drive engine to a rear-drive one, the performance enhancement of the power turbine and the incorporation of two channel FADEC(Full Authority Digital Engine Control) system for more reliable operation. Therefore, T700/701K engine must be qualified by Korean government in order to perform a flight in the country. Reflecting the influence of developing scope, the main requirements including performance and control are verified by test and analysis, while the requirement for module or component that is same to that of T700-701C/D are verified by similarity.

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